Electrodeposition

ABSTRACT

Nickel plating baths are improved by adding as brightening agent phenyl propiolic acid or the amide.  Nickel chloride, sulphate or fluoborate may be used.  Other additions referred to are wetting agents, acetyl acetone, saccharin, acetonyl acetone, diacetone alcohol, 2-butene-1,4-diol, methyl hydroxy butanone, sulphonated dibenzo thiophene dioxide, triphenyl methane, and nitrides both aliphatic and aromatic.  Base metals specified are copper and copper alloys, iron, and steel.

United States Patent 3,139,393 ELECTRODEPOSITION John A. Hartman, Deal-born, and Frank Passal, Detroit, Mich, assignors, by mesne assignments, to M & T Chemicals Inc, New York, N.Y., a corporation of Delaware No Drawing. Filed Nov. 22, 1960, Ser. No. 70,924 Y 18 Claims. (Cl. 204-49) The present invention relates to aqueous baths and processes for electrodepositing nickel.

It is an object of this invention to provide novel baths for electrodepositing nickel.

It is also an object of this invention to provide a novel process for electrode-positing nickel.

We discovered that semi-bright nickel deposits are electrodeposited from aqueous acid nickel plating baths containing as the brightening additive a small but effective amount of phenylpropiolic acid or phenylpropiolamide. Baths from which the semi-bright nickel deposits are obtained in accordance with the present invention have excellent leveling and covering power. The deposit is relatively ductile, and in appearance, is finely grained, milky, and lustrous. The deposit appears to be columnar in nature as contrasted with the general lamellar-type deposit characteristic of bright nickel. It has been found to have excellent corrosion resistance. The deposit may be buffed to a bright finish or it may be used as the basis for electrodeposition of a bright nickel deposit, resulting in a corrosion resistant duplex nickel electrodeposit.

Conventional baths and processes for electroplating nickel are described in Principles of Electroplating and Electroforming, Blum and Hogaboom, pages 362-381, revised third edition, 1949, McGraW-Hill Book Co., Inc., New York; and in Modern Electroplating, edited by A. G. Gray, the Electrochemical Society, 195 3, pages 299-3 55. The control and operating conditions, including the concentration of the bath ingredients, pH, temperature, current density, agitation, etc., of these conventional baths are generally applicable to the present invention. Almost all baths for electroplating nickel contain nickel sulfate; a chloride, usually nickel chloride; a bufiering agent, usually boric acid; and a wetting agent, e.g., sodium lauryl sulfate, sodium lauryl ether sulfate, and sodium 7-ethyl- 2-methyl-4-undecanol sulfate. Such baths include the well-known Watts bath and other baths containing as the source of the nickel a combination of nickel fluoborate with nickel sulfate and nickel chloride, or a combination of nickel fluoborate with nickel chloride. For most industrial purposes, a Watts-type bath containing about 300 g./l. (grams per liter) of nickel sulfate and about 60 g./ 1. of nickel chloride is preferred. Watts-type baths are generally within the concentration range noted in Table I.

TABLE I Watts-Type Baths Nickel sulfate 200 to 400 g./l. Nickel chloride 30 to 120 g./l. Boric acid 30 to 50 g./l. Temperature 30 to 65 C. pH 2.5 to 4.5 electrometric.

The addition of between about 0.025 g./ 1. and 0.4 g./l. of phenylpropiolic acid or of between about 0.025 g./l. and 0.5 g./l. of phenylpropiolamide, in the above bath results in baths useful for the electrodeposition of semi-bright nickel. When less than about 0.1 g./l. of the additive is used, the effect as a semi-brightening agent is proportionately decreased and becomes essentially non-effective at below about 0.025 g./l. The preferred range for obtain- 3,139,393 Patented June 30, 1964 ing best results for both additives is between 0.1 g./l. and 0.3 g./l.; optimum results are obtained at about 0.2 g./l. Due to slightly better deposit characteristics, phenylpropiolamide is preferred to phenylpropiolic acid.

We found that when nickel is deposited in accordance with standard conditions from baths containing phenylpropiolamide or phenylpropiolic acid under high current density conditions, the deposits are slightly more grainy and less lustrous. We further discovered that the entire conventional current density range, i.e., from about 0.5 a.s.d. (amperes per square decimeter) to about 12 a.s.d. may be used to obtain uniform lustrous semi-bright nickel electrodeposits when the bath contains, in addition to the phenylpropiolic acid or the phenylpropiolamide, an effective amount of one of the following additives: acetonylacetone (between 0.5 g./l. and 5 g./l., and preferably 2 g./l. to 4 g./l.); acetylacetone, between 0.5 g./l. and 5 g./l., and preferably 2 g./l. to 4 g./l.); methylhydroxybutanone (between 0.5 g./l. to 3 g./l., and preferably 1 g./l. to 2 g./l.); diacetone alcohol (between 0.5 g./l. and 2 g./l., and preferably 1 g./l. to 2 g./l.); and 2- butene-1,4-di0l (between 0.1 g./l. and 0.2 g./l., and preferably 0.1 g./l. to 0.15 g./l.). Of the foregoing, acetylacetone is preferred because of its low cost and adequate solubility characteristics (in excess of 20 g./l. in a Watts bath).

For the purpose of giving those skilled in the art a better understanding of the invention, illustrative examples are given. In each of the examples, an aqueous acidic nickel-containing bath was made up with the specified components. Preliminary and screening tests were run in the standard Hull Cell in which the cathode current density varies from 0 to about 12 a.s.d. Subsequent tests were made in a conventional cell with a moving cathode at various cathode current densities between 1 and 5 a.s.d. In Examples 1 through 14, the following was used as the base solution:

Nickel sulfate 300 g./l. Nickel chloride g./l. Boric acid 45 g./l.

Sodium lauryl sulfate 0.25 g./l. (with or without or mechanical agitation). Sod1um-7-ethyl-2-methyl- 4-undecanol sulfate 0.25 g./l. (with air agitation). Temperature 55 C.

Example Additive Amount,

Phenylpropiolle acid 0. 2 Phenylpropiolamide 0. 2 do 0.05 Phenylpropiolic acid 0.1 Phenylpropiolamide. 0. 45 6 Phenylpropiolie acid- 0.3 7 Phenylpropiolamide 0. 2

Acetylacetono 3 8 Phenylpropiolamide 0.2

Acetonylaeetoue 4 9 Phenylpropiolamide 0. 2 2-butene-1,4- 9.2 10 Phenylpropiolic acid. 0.2

Acetonylae one 2 11 Phenylpropiolamide. 0.1

Diaeetone alcohol 2 12 Phenylpr0piolarnide 0.2

Methylhydroxybutanoue 3 13 Phenylpropiolamide 0.1

Acetylaoet0ne 3 14 Phenylpropiolie aci 0.15

2-butene-L4-diol 0. 1

C Examples 15, 16, and 17 utilized the bath components noted hereinafter; other components and conditions were the same as used in Examples 1-4.

Deposits obtained from all the examples were sound semibright nickel with desirable deposit characteristics; those deposited from Examples 7-14 were superior in the high current density end of the Hull Test cathodes. Long term repetitive plating tests were run to establish the life characteristics of the baths. The baths have proven to be long-lasting with little breakdown of additives; no chemical or physical treatment was required to remove them. The concentration of the additive in the bath is conveniently determined by ultra-violet spectrophotometry. The drag-out products of this bath have been checked for compatibility with a number of bright nickel plating baths. In all cases, the drag-out products did not cause any adverse effect in the bright bath. It was found that both phenylpropiolic acid and phenylpropiolamide act as auxiliary brighteners in conjunction with the conventional sulfonated organic Secondary brighteners such as saccharin, sulfonated dibenzothiophene dioxide, and in conjunction with such primary brighteners as the heterocyclic, aliphatic, and aromatic nitriles, triphenylmethane, etc., to yield mirror-bright nickel. The semi-bright nickel electrodeposits are usually plated on copper or a copper alloy basis metal. However, they may be electrodeposited directly on such metals as iron, steel, etc.

As many embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention includes all such mod ifications and variations as come within the scope of the appended claims.

We claim:

1. An aqueous acid electrolytic bath containing soluble nickel salts for the electrodeposition of semi-bright nickel and containing as the semi-bright additive phenylpropiolamide in an amount between 0.025 g./l. and 0.5 g./ l.

2. A Watts-type electrolytic bath for the electrodeposition of semi-bright nickel, containing as the semi-bright additive (A) between 0.1 g./l. and 0.3 g./l. of phenylpropiolamide; together with (B) one auxiliary additive selected from the following group of five compounds in the amount indicated in parenthesis following the specified compound: acetonylacetone (0.5 g./l. to g./ 1.); acetylacetone (0.5 g./l. to 5 g./l.); methylhydroxybutanone (0.5 g./l. to 3 g./l.); diacetone alcohol (0.5 g./l. to 2 g./l.); and 2- butene-1,4-diol (0.1 g./l. to 0.2 g./l.).

3. A Watts-type electrolytic bath for the. electrodeposition of semi-bright nickel, containing as the semi-bright additive (A) between 0.1 g./l. and 0.3 g./l. of phenylpropiolamide; together with (B) one auxiliary additive selected from the following group of five compounds in the amount indicated in parenthesis following the specified compound: acetonylacetone (2 g./l. to 4 g./l.); acetylacetone (2 g./l. to 4 g./1.); methylhydroxybutanone (1.

g./l. to 2 g./l.); diacetone alcohol (1 g./l. to 2 g./l.); and

2-butene-1,4-diol (0.1 g./l. to 0.15 g./l.).

4. The bath as set forth in claim 3 in which the auxiliary additive is acetonylacetone.

5. The bath as set forth in claim 3 in which the auxiliary additive is acetylacetone.

6. The bath-as set forth in claim 3 in which the auxiliary additive is methylhydroxybutanone.

7. The bath as set forth in claim 3 in which the auxiliary additive is diacetone alcohol.

8. The bath as set forth in claim 3 in which the auxilary additive is 2-butene-1,4-diol.

9. An aqueous electrolytic bath for the electrodeposition of semi-bright nickel consisting essentially of about 300 g./l. of nickel sulfate, about 60 g./1. of nickel chloride, and about 45 g./l. of boric acid, and containing as the semi-bright additive between 0.1 g./l. and 0.3 g./l.

of phenylpropiolamide.

10.. A process for electroplating semi-bright nickel comprising electrodepositing nickel from a Watts-type electroplating bath containing'as the semi-bright additive,

. phenylpropiolamide in an amount between 0.025 g./l. and

11. A process for electroplating semi-bright nickel comprising electrodepositing nickel from a Watts-type electroplating bath containing as the semi-bright additive (A) phenylpropiolamide in an amount between 0.025 g./l. and 0.5 g./l.; together with (B) one auxiliary additive selected from the following group of five compounds in the amount indicated in parentheses following the specified compound:'acetonylacetone (0.5 g./l. to 5 g./l.); acetylacetone (0.5 g./l. to 5 g./l.); methylhydroxybutanone (0.5 g./l. to 3 g./l.); diacetone alcohol (0.5 g./l. to 2 g./l.); and 2-butene-L4-diol (0.1 to 0.2 g./l.).

, 1.2. A process for electroplating semi-bright nickel comprising electrodepositing nickel from a Watts-type electroplating bath containing as thesemi-bright additive (A). phenylpropiolamide in an amount between 0.1 g./l. and 0.3 g./l.; together with (B) one auxiliary additive selected from the following group of five compounds inthe amount indicated in parenthesis following the specified compound: acetonylacetone (2 g./l. to 4 g./l.); acetylacetone (2 g./l. to 4 g./l); methylhydroxybutanone (1 g./l. to 2 g./l.); diacetone alcohol (1 g./l. to 2 g./l.); and 2-butene-l,4-diol (0.1 g./l. to 0.15 g./l.).

13. The process as set forth in claim 12 utilizing acetylacetone as the auxiliary additive.

14. The process as set forth in claim 12 utilizing acetonylacetone as the auxiliary additive.

15. The process as set forth in claim 12 utilizing methylhydroxybutanone as the auxiliary additive.

16. The process as setforth in claim 12 utilizing diacetone alcohol as the auxiliary additive.

17. The process as set forth in claim 12 utilizing 2- References Cited in the file of this patent UNITED STATES PATENTS 2,781,305 Brown Feb. 12, 1957 2,849,353 Kardos Aug. 26, 1958.

FOREIGN PATENTS 1,141,135 France Mar. 11, 1957 525,847 Great Britain Sept. 5, 1940 525,848 Great Britain Sept. 5, 1940 

1. AN AQUEOUS ACID ELECTROLYTIC BATH CONTAINING SOLUBLE NICKEL SALTS FOR THE ELECTRODEPOSITION OF SEMI-BRIGHT NICKEL AND CONTAINING AS THE SEMI-BRIGHT ADDITIVE PHENYLPROPIOLAMIDE IN AN AMOUNT BETWEEN 0.025 G./L. AND 0.5 G./L. 